The present invention relates to an intermediate bow of a folding top, and, more particularly, to an intermediate bow which is fastened, via cantilevers arranged at its ends, to lateral roof-frame parts of the folding-top structure such that, during the opening of the folding top, the intermediate bow is loaded with a pivoting effect to assure automatic storage of the folding top without damage.
An intermediate bow is already know, for example, from German Patent Specification 3,724,532. This intermediate bow is connected to the folding top covering which spans the bow. During the closing of the folding top, the bow is taken up by the increasingly taut folding-top covering and is thereby positively pivoted out of its stowage position directed rearwards into its tensioning position directed forwards. It is, therefore, also referred to as a drag bow.
When the folding top is being opened, and the folding-top covering relaxes and arranges itself in folds, the drag principle can be adopted to only a limited extent for the necessary backward pivoting movement of the intermediate bow. In a first phase of the opening operation, the folding-top covering lifts off from the lateral roof frames of the folding-top structure in the region of the connection with the intermediate bow and thereby initiates a partial backward pivoting movement of the intermediate bow. It is nevertheless impossible to ensure that the intermediate bow goes beyond its turn dead center towards the stowage position, after which is could be pivoted further right into its stowage position by the folding pressure of the structure parts swinging onto one another.
Where the folding top is actuated manually, this situation results in unsatisfactory handling, because the intermediate bow may need to be pushed rearwards beyond its turn dead center by manual action.
If, in contrast, automatic folding-top actuation, such as a hydraulic drive an insufficient pivoting advance of the intermediate bow when the folding top is being opened can lead to serious damage to the intermediate bow itself and/or to adjacent structure parts.
An object of the present invention is, therefore, to provide a folding top intermediate bow which ensures that, during the opening operation of the folding top, the intermediate bow will be stowed automatically and without any damage, irrespective of the method of actuating the folding top.
The foregoing object has been achieved in accordance with the present invention by providing that during the opening operation of the folding top, the intermediate bow is loaded with a pivoting effect beyond its critical turn dead center.
In a presently preferred embodiment of the present invention, a pivoting drive consists of a spring accumulator drive which, when the folding top is being closed, can be tensioned by the advance of the folding-top covering. The spring-accumulator drive can consist, for example, of a tension-spring arrangement between a bow tube of the main bow and the intermediate bow. With the folding top closed, the tension springs are stretched longitudinally by an amount matched to the pivoting advance of the intermediate bow. The freedom of constructive design would be restricted considerably by this, however, since, with the folding top closed, the tension springs preferably consisting of flat rubber bands have to extend at a sufficient moment distance from the pivot axis of the intermediate bow.
Moreover, for stability reasons, it has been found desirable to provide a pair of leg springs for the pivoting drive of the intermediate bow. In each case, the spring winding of the leg spring can take a course concentric relative to the circular path of the intermediate bow as the intermediate bow pivots about a hinge bearing on a roof-frame link, the intermediate bow being coupled to the hinge bearing by a cantilever, an axis from the hinge bearing to the intermediate bow being a pivot axis of the intermediate bow. A protective arrangement of the respective spring windings between the cantilever and the associated roof-frame link is also possible.
A favorable dimensioning of the leg springs can be obtained if, in the expanded state, their spring legs form an angle markedly smaller than the pivot angle of the cantilevers between the tensioning position and the stowage position.
If the roof-frame links of the folding top are pivoted in the width direction of the folding top during the operation of swinging the links in and out, that spring leg of the leg spring supported on the cantilever should be slide-guided on the cantilever.
A particularly simple and good sliding guide comprises a hook-shaped bend of the spring leg which, partially surrounding the circumference of the cantilever, is mounted slidably on this. The cantilevers are especially suitable as sliding counterparts for the associated spring leg if they consist of links of round cross-section.